mysql学习二（常用函数）

• 字符串函数

mysql> select concat('aaa','bbb','ccc');
+---------------------------+
| concat('aaa','bbb','ccc') |
+---------------------------+
| aaabbbccc                 |
+---------------------------+
1 row in set (0.02 sec)


mysql> select insert('beijng2008you',12,3,'me');
+-----------------------------------+
| insert('beijng2008you',12,3,'me') |
+-----------------------------------+
| beijng2008yme                     |
+-----------------------------------+
1 row in set (0.00 sec)

• 数值函数

mysql> SELECT MOD(15,10),MOD(1,11),MOD(null,10);
+------------+-----------+--------------+
| MOD(15,10) | MOD(1,11) | MOD(null,10) |
+------------+-----------+--------------+
|          5 |         1 |         NULL |
+------------+-----------+--------------+
1 row in set (0.01 sec)


mysql> select rand(),rand();
+---------------------+--------------------+
| rand()              | rand()             |
+---------------------+--------------------+
| 0.08019654553401893 | 0.8553781629124453 |
+---------------------+--------------------+
1 row in set (0.01 sec)

• 日期和时间函数

mysql> select curdate();
+------------+
| curdate()  |
+------------+
| 2018-09-11 |
+------------+
1 row in set (0.00 sec)

mysql> select curtime();
+-----------+
| curtime() |
+-----------+
| 11:11:12  |
+-----------+
1 row in set (0.00 sec)

mysql> select now();
+---------------------+
| now()               |
+---------------------+
| 2018-09-11 11:11:21 |
+---------------------+
1 row in set (0.00 sec)

• 流程函数

• 其他常用函数